Method of treating ores



N0V- 14, 1961 F. J. cLAwsoN Erm. 3,008,574

METHOD 0F TREATING'ORES 2 Sheets-Shee'I 1 Filed June 50, 1958 Urll nu u un 'I DIJE Nov. 14, 1961 F. J. cLAwsoN ETAL 3,008,574

METHOD oF TREATING oREs Filed June 50, 1958 2 Shee'cs-Shef-VrI 2 PIE. E

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United States Patent C 3,008,574 METHOD OF TREATING ORES Floyd J. Clawson, Glenview, Ill., and Walter O. McClintock, Bartow, Fla., assignors to International Minerals & Chemical Corporation, a corporation of New York Filed June 30, 1958, Ser. No. 746,655 3 Claims. (Cl. 209-12) The presen-t invention relates generally to improvements in the art of beneiiciating ores. The invention more particularly relates to a method and apparatus for beneficiating mica ores, barite ores, feldspar ores, kaolin ores, and potash ores.

It has been discovered that certain silt deposits in river beds and lake bottoms in the southeastern part ot the United States are rich in mica deposits. These silt deposits contain mica in small flakes. The mica iiakes are a dull, pearly gray color with a yellowish tint. The mica is associated with large amounts of slimes and the slimes are preferably removed before further beneficiating the mica. I,

Large deposits of barite ore are also found in silt deposits of certain river beds and lake or pond bottoms. These ores are also preferably deslimed before the barite is further beneiiciated.

Many kaolin ores, and other associated kaolin minerals in the kaolin division, according to Danas system of mineralogy, occur in a finely divided .form and the present invention may be utilized to recover, tine size and/or upgrade such ores.

Feldspar ores also contain slimes which are preferably removed before further beneiiciating the ore.

Potash ores, such as, for example, sylvite, sylvinite, langbeinite, as Well as other associated potash minerals, also contain slimes. These potash minerals are usually beneciated in a flotation operation utilizing'ilotation re-V agents, and it is preferred to remove a large portion of the slimesl before the flotation operation,vsince the presence of slimes increases the amount of yflotation reagent which mus-t be used, thereby increasing the cost` ofy the flotation process. l

It is desirable to remove the slimes from these ores especially when the rore is to be beneficiated in a otation operation. The slime particles are very fine, have a large surface, and tend to absorb the reagent, thereby making the cost of using a reagent prohibitive. Further, most beneficiation methods do not operate efficiently on '-200 mesh material. In many instances, the -150 meshmaterial is preferably removed. Since slimes are predominantly 200 mesh, they are removed in an operation which separates the +200 mesh material from the tine -200 mesh material. The removal of line mate-V rial, which includes the slimes, is usually referred to as a desliming operation.

-In the description of this invention, for the sake of simplicity, the iine material will be referred to as the -200 mesh fraction and Ithis fraction will also contain slimes. It will be understood, however, that the sizing of the line material maybe on a diierent mesh, for example, 150 mesh, 270 mesh, 325 mesh, etc.

The ores, before being amenable to treatment in theprocess of this invention, must be in a Water slurry form and, therefore, if the ore, as delivered to the plant, is not in water slurry form, ,a water slurry "of the ore is prepared. The ore is presen-t in the pulp inydivided form. Many of the phosphate ores, barite ores, kaolin ores, etc., Iare recovered in nely divided form. The ore,

however, may be crushed, ground, or otherwise comminuted when desired. The feed to the process of the present invention is ltherefore a water slurry of the ore, such as mica, barite, feldspar, kaolin, or potash ore. The water slurry is usually denominated a pulp and will be herein'so referred to.

The present invention is concerned with the removal of slimes and fine material from a pulp and it is, -accordingly, an object of this invention to provide a method and apparatus for desliming slime-containing ores.

Another object of the present invention is to provide a method and apparatus for removing 200 mesh mate'- `rial from ores.

A further object of the present invention is to provide a charge to an ore beneiiciation process which is substantially free of -200 mesh material.

-It is an additional object of the invention to provide a process and apparatus for desliming ores which are suitable for installation in a conventional commercial plant.

lt is a specific object of the present invention to provide a process and apparatus for removing slimes from mica found in silt deposits. i

It is another speoiiic object of this invention to provide a process and apparatus for desliming slime-containing barite ores.

A further specific object of this invention is to provide a process and apparatus for desliming feldspar ores.

It is still another speciiic object of the present invention to provide a method of recovering kaolin minerals from kaolin ores.

An additional speciiic object is to provide a method and apparatus for desliming and tine-sizing potash ores and associated minerals.

Fur-ther objects and advantages of the present invention will be apparent from the following description and drawings which illustrate one form of the invention.'

-In the drawings:

FIGURE l is a front elevational View, partly in section, of an apparatus embodying various features of the present invention;

FIGURE 2 is a sectional View of the apparatus shown in FIGURE l taken substantially along line 2-2 of FIGURE l; and l yFIGURE 3 is an enlarged plan view of a portion of a flat screen used in the apparatus shown in FIGURES l and 2.

KNOW, in accordance with this invention it has been discovered that -a slime-containing ore can be eiciently deslimed by passing a Water slurry of the ore down an inclined flat screen, subjecting at least a portion yof the material which passes through the iiat screen to a hydro"- coning operation and recovering the denser phase from the hydroconing operation. The less dense phase may also be recovered as a product or may be disposed of as waste.

One of the early objections to any use of hydroconing in a commercial plant was the high cost of the power necessary to supply the pulp to the cones in the large volumes and high pressures ybelieved necessary for eiiicient operation of the `cones. lIn the present invention,

this objection is removed since the pulp is tiowed only the rate of ow thereto had to be relatively constant. The llow of the ore into a commercial plant however is usually erratic and it, therefore, was not believed to be practical to use hydrocones in such an operation. In the present invention, a substantially uniform rate of flow of material at a. substantially constant pressure is provided to the hydrocones.

In accordance with this invention, the pulp of the ore is pumped to an elevated position so that the pulp may dcend under gravity flow down an inclined flat screen for a at screening operation. It has been determined that the material passing through the -at screen is particularly suitable for use in a hydroconing operation. The material passing through the screen is usually denominated the underflow. Material which passes through the llat screen, and which is not hydroconed, may be further processed as hereinafter described. The combination of at screening and hydroconing has proved to be highly efllcient and has provided a particularly suitable feed for a beneciation operation utilizing llotation reagents.

The invention may readily be understood by reference to the drawings which illustrate a method and apparatus for beneiiciating ore embodying various features of the invention; The drawings are intended merely to illustrate the general application of the instant invention and are not to be considered a limitation thereon. Modifications of the process and apparatus illustrated in the drawings, while employing the principles of the instant invention, will be apparent to those familiar with the art.

Referring to the drawings, an aqueous pulp is pumped to an elevated position through conduit 11 and passes into a receptacle, or hopper box, or surge tank 13. The surge tank`13 is provided to widen the stream of polp and to distribute it at a more even rate of llow to a at screenlS.

The surge tankll3 is of the open top type and one of the upwardly extending Walls 17 is shorter than the others so that the pulp in the tank flows over the top edge of this wall 17. The surge tank 13 is supported in an elevated position by suitable support members 19. The pulp overflowingk from the surge tank 13 is directed to an upper portion of the inclined fiat screen 15.-

The screen is preferably of the llat surfaced type, sinceithas been determined that a flat screening operation produces good results. The ilat screen 15 is usually punched plate or sheet metal. The flat screen 15 preferably has slotted holes 21 (FIG. 3) therein and may have the slots positioned hit-and-miss sideways, hit-and-miss endways or in straight parallel rows as is illustrated in FIGURE 3. A further discussion and illustration of slots of this typein flat screens mayV be found in Taggart, Handbook of Mineral Dressing, chapter 7, pages 14-15 of the. 1945 edition. The flat screens are preferably positionedso that the long dimension of the slotted holes 21 is parallel to the main direction of lloW along the surface of the flat screen as shown in FIGURE 3. The flat screen is preferably fabricated in parts such as part 15a illustrated in FIGURE 3 so that only the parts that Wear out need be replaced. Further, by fabricating the flat screenin parts, the replacement operation is facilitated. InV a commercial embodiment of this apparatus, each part of at screen was 1A plate 3 x 21/2, and the holes were 1 mm. xr/z". The flat screen is inclined downwardly from the surge tank 13 at an angle suilicient to insure that substantially all of the large particles in the pulp will ow downthe .flat screen. In order to facilitate the llow of large particles down the flat screen, suitable water spray nozzles (not illustrated) may be provided to direct the large particles down the yllat screen. An inclination ofV from about .20 to about 45 from the horizontal for the flat screen is preferred. The length of the flat screen measured downward along the incline is preferably sufficient to insure that substantially al1 of the material which is vsmaller than the size of the holes in the flat screen passes through the holes before the material drops off of the` lower endl of the screen. As hereinbefcre set forth,

the screening is preferably on l mm. and, accordingly, the width of the slots is preferably l mm. Other sizes may, however be used.

As the pulp flows down the llat screen 15, most of the Water and -1 mm. material passes through the openings in the flat screen and the |1 mm. material drops off the lower edge 25 of the flat screen and is collected in a pair of funnel-shaped hoppers 27. Thus the underu sized material, i.e., -l mm. material, passes through the screen while the oversized material, i.e., -l-l mm. material, drops off the lower edge of the screen.

The -1 mm. underllow is collected in a. trough 29' which is defined by vertical walls 31, the vertical wall 17, a bottom inclined wall 33 and a lower transverse wall or baille 35. The baille 35 extends across the box-like structure of the trough 29 between the walls 31 and extends from the bottom wall 33 up to the flat screen 15. The baille 35 is transverse to the incline of the flat screen 15.

In accordance with the present invention, a means 37 is provided below and 'under the llat screen to collect the -l mm. material passing through the flat screen. The baille 35 is positioned under the =llat screen to split or divide the material passing through the flat screen, that is, the baille 35 divides the material passing through the at screen so that material passing through the upper portion of the flat screen is separately collected in the collecting means 37 and material passing through the lower portion of the flat screen is separately collected in the funnel-shaped hoppers 27. It should be noted that the baille 35 ispositioned in a lower region of the flat screen 15 so that the greater length ofthe flat screen 15 is above the baille 35 and only a short length of the llat screen 15 is positioned below the baille 35. The -l mm. material which passes through the flat screen 15 above the baffle 35 contains a large portion of 15,0 mesh material and is particularly amenable to treatment in a hydrocone. This material is collected in the collecting means 37. The means 37, illustrated, includes the inclined bottom wall 33, the baille or weir splitter 35 which extends upwardly from the inclined bottom wall 33 and between the vertical walls 31. The box-'like structure 29 is suitably supported by the support ymembers 19.

The -1 mm. material which passes through the upper part of the flat screen 15 and which is separately collected above the baffle 35 in the collecting means3|7 is Wtvithfv drawn from the collecting means through a conduit 39. The rateof withdrawal of -l mm. material throughthe conduit 39 is usuallyless than the amount of'material coming through the portion of the llat screen above the baille 35 and, therefore, some material flows over the upper edge of the baille 35'. The level of liquid in the collecting means 37 is, therefore, substantially atthe upper 2 of the drawing, the material in the collecting means 37 is passed by gravity dow directly into the hydrocones 45. The feed material is fed tangentially into the hydrocone 45 through the connecting or feed inlet conduits 43. In the hydrocones 45, a separation is made in the cone-- shaped section 49 by the action -of centrifugal and centripetallv forces. The heavieror denser portion ofthe material leaves the cone as underflow at the apex of the cone and is withdrawn through a conduit 51. The lighter or less dense portion of the feed leaves the cone 45 as overflow through a conduit 513 which connects with the top of the cone. A further discussion of cones of this type may be found in Perry, Chemical Engineers Handbook, 3rd edition. The cones are suitably supported on. the Support members. 19Y

The overliow conduits 53 empty into a manifold conduit 55. A conduit 57 is connected with a lower portion of the manifold conduit 55 and is provided to conduct the material in the manifold conduit 55 to a suitable disposal point. When processing kaolin ores, the finely divided kaolin will be removed as overiiow from the cones 45 through the overflow conduits 53. The couduit 57, therefore, carries finely divided and beneciated kaolin ore to a suitable recovery point where the ore may be further beneiiciated when desired. When processing other slime-containing ores such as mica ores, barite ores, feldspar ores and potash ores, the overow from the cones 45, removed through conduits 53, will contain slimes and these slimes are usuallly discarded as waste. Accordingly, the conduit 57 will conduct the material in the manifold conduit 55 to Waste. Another conduit 59 is also connected to the manifold conduit 55. Conduit 59 is provided to handle any excess material which conduit 57 may not be able to handle. Conduit 59 connects with disposal conduit 61 which conducts the material to a suitable Waste disposal point.

The underflow from the cones 45 is removed through conduits 51, and the conduits 51 are connected to a pair of manifold conduits 63. The manifold conduits 63 conduct the underow to tanks 65. The material in tanks or containers 65 may be recovered through conduits 67. When processing mica ores, barite ores, feldspar ores, and potash ores, the material in the tanks 65 is substantially slime-free, and therefore the material lwithdrawn through conduits 67 may be directly beneciated without further treatment. The material in the conduits 67 is particularly suitable as feed for a beneiiciation process utilizing otation reagents.

Referring back to the upper structure -and the flat screening operation, the material in the funnel-shaped hoppers 27, which includes the overflow of the fiat screen and the underow of the at screen below baie 35, is conducted through conduits 69 and introduced into a pair of inclined trommels 71. The trommels 71 have a screen 73 about their outer circumference and the trommels are rotated on inclined shafts 75 by a sui-table source of power (not illustrated). In a commercial embodiment of the apparatus, the openings in the screens were 5/32. The material passing through the tia-t screen 15 below the bafe 35 is substantially free of -200 mesh material. 'Ihe overflow material falling olf the lower end 25 of the lat screen 15 is also substantially free of -200 mesh material. Therefore the material in conduit 69 which is introduced into the trommels 71 is also substantially free of -200 mesh material. Accordingly, the material passing through the screen 73 of the trommel 71 is also substantially free of 200 mesh material. The material passing through the screens 73l is collected in pans or troughs 77 positioned below the trommels. The pans have V-shaped bottoms. The material in pans 77 flows through conduits 79 and is introduced into the tanks 65 into which the underflow from the cones 45 is also introduced. The material which does not pass through the screens of the trommels 71 is removed from the lower end thereof and iiows over a Hat inclined deck 81 -and drops into conduit 61. 'I'he conduit 61 conveys the material to a suitable disposal point.

A commercial embodiment of this invention was constructed to beneciate a slurry of slime-containing silt deposit mica recovered in a dredging operation from a lake bottom located near Greenville, Tennessee. The slurry had the following size analysis:

The slurry was pumped to an elevated position and was passed down an inclined at screen. The screen had 1 mm. x V2" holes punched therein and the angle of inclination was about 27. -100 gallons per minute of the screen underflow was passed by gravity liow into an 8" diameter hydrocone. The overow from the hydrocone was 70 gallons per minute and contained 63.3% of the 200 mesh material. The cone underliow showed that 93.3% of the meshr material was recovered.

The above results indicate that a very good separation occurs at about 200 mesh. On examination of the cone products, it was found that almost ail of the organic material which went through the flat screen was rejected by the cone with the slmes.

The description of the invention utilized specific reference to certain process and construction details; however, it is to be understood that such details are illustrative only and not by way of limita/tion. Other Imodifications and equivalents of the invention will be apparent to those skilled in the art from the foregoing description.

Having now fully described and illustrated the invention, what is desired to be secured and claimed by Letters Patent is set forth in the appended claims.

We claim:

l. A method of desliming a slime-containing ore which comprises pumping a slurry of said ore to an elevated position, passing said slurry from said elevated position down an inclined at screen to discharge oversized material from the surface of said screen, collecting undersized material which passes through the inclined fiat screen in a collecting zone defined beneath said screen, overflowing undersized material from said collecting zone and recombining the overtiowed undersized material from said collecting zone with said oversized material to maintain a substantially constant pressure head of undersized material retained in said collecting zone, directly iiowing the material retained in said collecting zone by gravity iiow at a substantially uniform rate and at a substantially constant pressure provided by said pres sure head to a hydroconing operation, and recovering the denser phase from the hydroconing operation.

2. A method of desliming slime-containing silt deposit mica which comprises pumping a water slurry of said silt deposit mica to an elevated position, passing said slurry from said elevated position down an inclined at screen to discharge oversized material from the surface of said screen, collecting undersized material which passes through the inclined fiat screen in a collecting zone defined beneath said screen, overflowing undersized material from said collecting zone and recombining the overflowed undersized material from said collecting zone with said oversized material to maintain a substantially constant pressure head of undersized material retained in said collecting zone, directly flowing the material retained in said collecting zone by gravity iiow at a substantially uniform rate and at a substantially constant pressure provided by said pressure head to a hydroconing operation, and recovering the denser phase from the hydroconing opera-tion.

3. A method of beneiiciating a kaolin ore which comprises pumping a water slurry of said kaolin ore to an elevated position, passing said water slurry from said elevated position down an inclined flat screen to discharge oversized material from the surface of said screen, collecting undersized material which passes through the inclined flat screen in a collecting zone defined beneath said screen, overiiowing undersized material from said collecting zone and recombining the overowed undersized material from said collecting zone with said oversized material to maintain a substantially constant pressure head of undersized material retained in said collecting zone, directly flowing the material retained in said collecting zone by gravity flow at a substantially uniform rate and at a substantially constant pressure provided by n 7" said pressure head to a hydroconing operation, and recovering the less dense phase from the hydroconing operation.`

References Cited in the le of this patent UNITED STATES PATENTS 675,057-v Edison May 2s, 1901 1,700,925 Dezurik Feb. 5, 1929 2,163,927 Wright June 27, 1939 8 Leemn et a1. Dec. 24, 1957 Stinson June 2,1, 1960j FOREIGN PATENTS- Canada Sept, 7, 1954 Canada Sept. 28, 1954 Great Britain Mar. 23, 1955 Great Britain Mar. 23, 1955 

1. A METHOD OF DESLIMING A SLIME-CONTAINING ORE WHICH COMPRISES PUMPING A SLURRY OF SAID ORE TO AN ELEVATED POSITION, PASSING SAID SLURRY FROM SAID ELEVATED POSITION DOWN AN INCLINED FLAT SCREEN TO DISCHARGE OVERSIZED MATERIAL FROM THE SURFACE OF SAID SCREEN, COLLECTING UNDERSIZED MATERIAL WHICH PASSES THROUGH THE INCLINED FLAT SCREEN IN A COLLECTING ZONE DEFINED BENEATH SAID SCREEN, OVERFLOWING UNDERSIZED MATERIAL FROM SAID COLLECTING ZONE AND RECOMBINING THE OVERFLOWED UNDERSIZED MATERIAL FROM SAID COLLECTING ZONE WITH SAID OVERSIZED MATERIAL TO MAINTAIN A SUBSTANTIALLY CONSTANT PRESSURE HEAD OF UNDERSIZED MATERIAL RETAINED IN SAID COLLECTING ZONE, DIRECTLY FLOWING THE MATERIAL RETAINED IN SAID COLLECTING ZONE BY GRAVITY FLOW AT A SUBSTANTIALLY UNIFORM RATE AND AT A SUBSTANTIALLY CONSTANT PRESSURE PROVIDED BY SAID PRESSURE HEAD TO A HYDROCONING OPERATION, AND RECOVERING THE DENSER PHASE FROM THE HYDROCONING OPERATION. 